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Haywood, Carl N. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume 75 (1987)

Bouchard, Roy; Madsen, John D.
The aquatic macrophyte community of Black Earth Creek, Wisconsin,   pp. 41-56 PDF (6.4 MB)

Page 41

The Aquatic Macrophyte Community of Black Earth Creek, Wisconsin 
Roy Bouchard and John D. Madsen 
Abstract. The aquatic macrophyte community of Black Earth Creek, Wisconsin,
was studied in June and July of 1985 and compared to data collected in 1981.
Macrophyte distribution was examined by the line intercept method, with macrophyte
cover negatively correlated to light reduction by tree canopy. The dominant
species in the stream was Potamogeton cnispus. Other species included P.
pectinatus, P. vaginatus, Elodea canadensis, Ranunculus longimostnis, Hypemicum
boneale and filamentous algae, namely Rhizoclonium sp. Average total cover
of all macrophytes was 55.6%. Cover of macrophytes was only slightly lower
in 1985 than in 1981, which was thought to be due to random population fluctuations
rather than directional change in the community. Macrophyte biomass was estimated
at three unshaded stations. Maximum macrophyte biomass was 789 g dw m2, with
no relation found between biomass and the inflow of a sewage treatment plant.
Samples of Potarnogeton cnispus and Rhizoclonium sp. analyzed for tissue
phosphorus indicated that plants are not near limiting concentrations for
P; rather, present data indicate that light availability limits the growth
of macrophytes in Black Earth Creek. Oxygen mass balance was used to estimate
community photosynthesis and respiration, and the macrophyte/epiphyte contribution
to community respiration estimated by in situ incubations. Macrophyte/epiphyte
respiration contributed 47% to 68% of community respiration. The PIR ratio
was 0.62, indicating a heterotrophic stream community. 
 quatic macmophytes are an important and habitat for macmoinventebmates and
component of stream ecosystems, other small organisms, as well as protecinfluencing
physical, chemical and bio- tion for large fish species. Macmophytes logical
processes. Aquatic macmophytes increase stream productivity beyond stabilize
the stream substrate, reducing energy gained by allochthonous inputs. In
turbidity and erosion. They also increase addition to these benefits, macmophytes
deposition of suspended solids, further provide surface area for microbes,
which reducing turbidity, and oxygenate the contribute significantly to many
chemical water by means of photosynthesis. Stream processes in the stream,
such as nitnificachannels deepen and current increases tion, respiration,
and decomposition. 
between adjacent plant beds, improving However, excess growths of macrohabitat
diversity. Aquatic macmophytes phytes can also create problems for the and
attached epiphytic algae provide food stream ecosystem. Bank-to-bank growths
of aquatic macmophytes will slow current 
John D. Madsen, formerly at the University of , 
Wisconsin-Madison, is now a research associate at velocities, causing flooding
and siltation. 
the Fresh Water Institute, Rensselaer Polytechnic Homogeneous growths of
Institute, Troy, New York. species reduce habitat heterogeneity. 
Roy Bouchard is a member of the Maine Depart- Most importantly, excessive
ment of Environmental Protection. growths create large daily dissolved oxy

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